The Liver Center at Texas Children's Hospital/Baylor College of Medicine (TCH/BCM) has been an active participant in BARC and CLiC, and is excited by the opportunity to continue participation. The overarching aims of this Center are to help advance the clinical, research, and educational goals of the ChiLDREN grant. Aim 1: Continued Clinical Center participation in all aspects of ChiLDREN. This Center has participated in all BARC &CLiC programs since 2005, as well as the CF Liver Disease Consortium. We Aim to continue our participation, which has provided high levels of enrollment into BARC (POO3, P004, POO5) and CLiC. The clinical infrastructure is broadly supportive, and the personnel experienced, which, along with centralized care and research, allows this Center a high level of enrollment and longitudinal follow-up. We will also engage in all aspects of observational and interventional trials in ChiLDREN. Aim 2: Explore the genetic determinants of adaptation to pediatric liver disease. Among the unique aspects that determine outcomes of liver disease in infants and children, is the contribution of the individual's genetic makeup, best exemplified by the short timelines that underlie whether these children will adapt well or not. We hypothesize that by detailed, broad-based, unbiased exploration of individual patient genomic determinants (e.g., whole exome sequencing or focused studies of nuclear receptor pathways), we will be able to assign genetic categorization of children into those able to adapt well, and those who do not. Moreover, we expect this information to allow for targeted therapeutic discoveries. Aim 3: Design and initiate Phase 1 and 2 clinical trials exploring Nor-UDCA as a therapeutic agent in a variety of cholestatic and fibrosing liver diseases in children. Nor-ursodeoxycholic acid (Nor-UDCA), a side chain modification of UDCA, is currently undergoing Phase 1 trials in Europe for cholestatic liver diseases in adults. Nor-UDCA enhances bile flow, perhaps through cholehepatic shunting. We hypothesize that Nor- UDCA will be a safe and effective therapeutic agent for select children with cholestatic liver disease;specifically those with ABCB4 disease, as well as children with BA &CFLD who have evidence of biliary fibrosis/cirrhosis or portal hypertension. Since there are currently no effective medical therapies for cholestasis, proper exploration of the safety and efficacy of this investigational agent would perfectly fit within the charge of ChiLDREN, and, arguably, is the only Consortium that could test such potential therapeutics.